Heretofore, a cemented carbide or a cermet in which ceramic particles (hard phase), such as WC (tungsten carbide) or Ti compounds, such as TiCN (titanium carbonitride) are bound with iron-group metals (binder phase), such as Co or Ni, are used for base materials of cutting tools.
In general, the cermet has high hardness because the cermet contains Ti compounds, such as TiCN, as a main hard phase, but the toughness thereof is lower than that of the cemented carbide containing WC as a main hard phase. Therefore, the cutting tool having a base containing the cermet has a narrow application range and is mainly utilized for low-load finish processing. In contrast, a composite material in which the cermet and the cemented carbide are laminated and bound has been proposed (Patent Literatures 1 and 2). Patent Literature 1 discloses a bound material obtained by individually producing a cemented carbide and a cermet, grinding the bonding surfaces thereof to reduce the surface roughness, laminating the cemented carbide and the cermet, and integrating the laminate by heating. Patent Literature 2 discloses a cemented carbide member obtained by laminating sintered compacts individually produced, and bonding the same by electrically heating or, for further increasing the bonding strength, by laminating green compacts individually produced, and sintering the laminate.    [Patent Literature 1]: Japanese Unexamined Patent Application Publication No. 6-240308    [Patent Literature 2]: Japanese Unexamined Patent Application Publication No. 7-207398